1. Field of the Invention
The invention is used to improve/repair the durability of open-air located objects such as piers, pillars, pipes, or other cylindrically symmetrical shaped objects, or to rehabilitate their mechanical attributes after damaging events. The adhesive of the invention can also be used to repair certain small irregularities on the surfaces of enforced objects. The adhesive can be prepared, used and hardened at the location of the enforced objects and while the objects are fully operating, even if the temperature is relatively cold, for example, at about 0° C.
2. Description of Related Art
Equipment and buildings are the victim of erosion, and consequently require repair and restoration. Due to erosion and corrosive effects, objects (such as piers, pipes, pillars, etc.) can have weakened structures or mechanical attributes. To repair these weaknesses, we often use bands of various composition, which are applied on the whole surface of the damaged structure, or just on the location where repair is necessary.
Numerous patents are directed to materials containing glass fiber strengthening materials in resin matrixes for enforcing bands. According to Canadian Pat. No. 2,028,524 and U.S. Pat. No. 4,700,752 for example, bands are made of a resin polyurethane-epoxy- or an embedded unsaturated poly-ester resin matrix, which provide fiber-optic enforcing materials having improved tensile strength.
One procedure is rotating the target object to give the glass fiber band a “resin bath” and to reel the object with it, thereby creating an enforcing band. Warming is usually used to harden the resin in the band. This procedure can only be applied in ideal circumstances. It isn't useable for large open-air located objects (large piers, pipes, pillars are very difficult if not impossible to rotate).
Another method for enforcing objects separates the embedded glass fiber in resin and applies the band on the surface of the object. This sort of action requires three steps, the first being embedding the glass fiber in the composite matrix (the resin). The second step includes reeling this pre-made, impregnated composite (prepreg) on the object in need of strengthening. The third step is solidifying the band. This is usually resolved by the heat transfer.
These procedures have several practical issues. One of the issues is positioning parallel enforcing strings perpendicular to the direction of the body of the object. The geometry of the parallel strings is also a problem because the cross-section of the band is smaller between the strings then in the position of the greatest diameter of the string. As a result, the band is uneven, irregular, and ribbed in its lengthwise direction. It is recommended for multi-thread bands that the “top of the wave” sections are implemented in the “bottoms of the waves”. This way the band is continuous and there won't be any open spaces in the band's structure. The correct positioning of the strings can improve the strengthening effect and the distribution of the matrix-material on the whole length of the band. This procedure requires extreme attention and the participation of the human workforce.
The formerly known procedures can't be used in some circumstances, because of bad weather and in other situations such as underground gas pipes in fast streams, or under high pressure. The rocks surrounding these pipes are constantly below 10° C. regardless of the season or the weather, although the initiators used to harden the composite coating are activated by the heat. For this effect to happen in the opportune time, heat is introduced through the outer layer of the prepreg material.
The composite band has a relatively reduced heat-transfer so it loses a huge amount of heat because of the cold surroundings and because of the transported medium's speed. The temperature in the immediate vicinity of the pipe is mostly induced by the pipes inner temperature. Because of the great parasite currents in the pipe, there is a big amount of heat transferred to the outer surroundings. Heating patrons are placed on the surface of the band (for helping the chemical hardening process) because of the reduced heat-transferring ability of the band's materials. The walls of the pipe receive very little heat through the composite material, because the inner medium transports most of it. A steady state develops with two extreme temperatures on the walls of the pipe (0-10° C.) and the exterior part of the band (130-135° C.). The initiator substance which helps harden the unsaturated polyester resin requires a minimum of 50-60° C., but as we saw the layer of the resin placed right in the vicinity of the walls of the pipes doesn't reach that temperature, so the initiator substance isn't efficient.
Those procedures which are based on heat-based polymerization of the band's structure don't work under the described circumstances, because the band's material (or part of the material) doesn't solidify properly or at all.
There have been attempts to dispose of these difficulties; like pre-making the composite band, already hardened, solidified and in the shape of a roll. (U.S. Pat. No. 5,518,568; U.S. Pat. No. 5,677,046; U.S. Pat. No. 5,683,530; U.S. Pat. No. 6,336,983). In this case, at least one side of the pre-made composite band is plain.
The clock spring shaped reeled composite band's radius of curvature is only half of the tile object's radius of curvature. When applying the pre-made band on the object, the flexible tension helps fix the band on the object.
The solid, rigid composite band's usage is problematic if the surface of the enforced object isn't regularly even. This can cause a problem between the composite band and the surface of the object, they won't stick together. The space between the two surfaces has to be filled with an adhesive. The bond made in this way is not as solid as it would be in the case of an object with even surface. Because of this, the surface of the object has to be previously formed, smoothened; or the band has to be made of the composite prepreg which hardens at the place of the operations.
The welded seam problem could be resolved by the circular seam (U.S. Pat. No. 5,518,568). According to the U.S. Pat. No. 5,518,568, two separate bands are placed on the two sides of a welded seam, and a third band is placed on top and bridges the gap between the other two. Three full bands are built in the strengthening structure with this method.
The described patents have a rigid composite material. The pre-made prepreg is not plastic, so it's not suitable for covering the whole surface of the object's irregularities and curves.
The formerly known procedures have the following disadvantages:                the strengthening material's strings need to be positioned in a specific order, which is difficult and requires human assistance. This can't be done in outdoor surroundings.        they aren't suitable for large, open-air located objects.        the composite prepreg can not reticulate in cold (below 15° C.) or if the band connects to cold surfaces.        the solid rigid prepreg (clock spring) isn't suitable, (or only after numerous procedures which use material and energy) for covering any surface, with the irregularities, or the curves they might have.        